Conduit for projecting sand



Patented Cet. 27, 1931 eNiTED STATES PATENT OFFICE OTTO NAGEL ANDWILHELM KAEMPFER, OF DURLACH, GERMANY, ASSIGNORS TO BADISCHEMASCHINENFABRIK & EISEN GIESSEREI VOR-MAIS G. SEBOLD UND SEBOLD & NEFF,OF DURLACH, BADE, GERMANY CONDUIT FOR PROJECTING SAND Application ledMarch 2, 1929, Serial No. 344,082, and in Germany December 12, 1928.

Our invention relates generallf.7 to machines for projecting sand bymeans of compressed air, such as sand molding machines, and 1Sespecially directed to improvements in the conduit through which thesand and air current passes to the nozzle through which the mixture ofsand and air issues.

The conduit is usually in the form of a pipe or hose whose internaldiameter must "f be sutliciently large to avoid presenting eX- cessiveresistance to the current of sand and air flowing therethrough. At theoutlet end of the conduit the speed of this current must be suitablyincreased in order to attain the requisite velocity for projecting thesand and compacting it into the molds, lt has been proposed, heretofore,to bring about this increased speed of the sand and air eurrent byinserting in the conduit at or near its outlet end a section of pipehaving a bore of smaller diameter than that of the conduit itself, butthis expedient proved to be undesirable be'xause the inserted section ofpipe impeded the flow of air and frequently sensed choking of theconduit. i

The object of our invention is to obviate the defects of existingconstructions and to provide simple and eicient means for atining therequisite increase of speed of :.e sand and air current at the outletend of s cearge into the nozzle. The taper may eX- tend the entirelength of the conduit or only part thereoibujt must be suiiiciently longto effect the requisite speed acceleration.

Two embodiments of the invention are shown in the accompanying drawingsin which, Figure l is a fragmentary sectional View of a conduit, thebore of which is tapered near its outlet endA and Figure 2 is a similarview of a modified form in which the taper extends the entire length ofthe bore.

Referring to Figure 1 of the drawings, 10 is a merely conventionalrepresentation of a sand chest from which the sand is carried by airunder pressure through the hose 11 and the nozzle l2. The bore-13 of thehose is of uniform diameter from the chest to approximately the point13a where the gradual taper elfect or conicity starts and continues toapproximately the point 13", adjacent the nozzle 12, where the bore hasits smallest diameter.

In Figure 2, the chest 10 communicates with the hose 11a the bore orflow passage of which is gradually tapered or coned from the point 13cof largest diameter to the point 13d, adjacent the nozzle 12, ofsmallest diameter.

By the arrangement described and illustrated, no projecting obstacle ispresented to the flow of the sand and air, but the gradual decrease inthe size or diameter of the flow passage constitutes highly efficientmeans for accelerating the speed and consequently the pressure of theissuing current of sand and air.

We claim:

In a device for projecting sand, the combination therewith, of a sandchest and a nozzle having a uniform bore, of a conduit connected toestablish communication from the chestto the nozzle and provided with auniform bore at the sand chest end and tapered to its smallest diametercorresponding with the bore of the nozzle at the nozzle end, wherebysand carried by air under pressure from said sand chest through saiduniform and tapered bore of the conduit until it has reached itsgreatest velocity at the nozzle end. 1

In testimony whereof we aflix our signatures.

OTTO NAGEL. VILHELM KAEMPFER.

